Maternal serum inhibin A can predict pre-eclampsia

Evaluation of first trimester maternal serum inhibin-A for preeclampsia screening

BACKGROUND

International professional organizations recommend aspirin prophylaxis to women screened high risk for preterm preeclampsia (PE) in the first trimester. The UK Fetal Medicine Foundation (FMF) screening test for preterm PE using mean arterial pressure (MAP), uterine artery pulsatility index (UTPI) and placental growth factor (PlGF) was demonstrated to have lower detection rate (DR) in Asian population studies. Additional biomarkers are therefore needed in Asian women to improve screening DRs as a significant proportion of women with preterm and term PE are currently not identified.

OBJECTIVES

To evaluate maternal serum inhibin-A at 11-13 weeks as an alternative to PlGF or as an additional biomarker within the FMF screening test for preterm PE.

STUDY DESIGN

This is a nested case-control study using pregnancies initially screened at 11-13 weeks for preterm PE using the FMF triple test in a non-intervention study conducted between December 2016 and June 2018. Inhibin-A levels were retrospectively measured in 1,792 singleton pregnancies, 112 (1.7%) with PE matched for time of initial screening with 1,680 unaffected pregnancies. Inhibin-A levels were transformed to multiple of the expected median (MoM). The distribution of log10 inhibin-A MoM in PE and unaffected pregnancies and the association between log10 inhibin-A MoM and gestational age (GA) at delivery in PE were assessed. The screening performance determined by area under receiver operating characteristic curves (AUC) and detection rates (DRs) at a 10% fixed false positive rate (FPR), for preterm and term PE was determined. All risks for preterm and term PE were based on the FMF competing risk model and Bayes theorem. Differences in AUC (ΔAUC) between different biomarker combinations were compared using the Delong test. McNemar's test was used to assess the off-diagonal change in screening performance at a fixed 10% FPR after adding inhibin-A or replacing PlGF in the preterm PE adjusted risk estimation model.

RESULTS

Inhibin-A levels in unaffected pregnancies were significantly dependent on GA, maternal age and weight and were lower in parous women with no previous history of PE. Mean log10 inhibin-A MoM in any-onset PE (p<0.001), preterm (p<0.001) and term PE (p = 0.015) pregnancies were all significantly higher than that of unaffected pregnancies. Log10 inhibin-A MoM was inversely but not significantly correlated (p = 0.165) with GA at delivery in PE pregnancies. Replacing PlGF with inhibin-A in the FMF triple test reduced AUC and DR from 0.859 and 64.86% to 0.837 and 54.05%, the ΔAUC was not statistically significant. AUC and DR when adding inhibin-A to the FMF triple test were 0.814, 54.05% and the -0.045 reduction in AUC was statistically significant (p = 0.001). At a fixed 10% FPR, replacing PlGF with inhibin-A identified 1 (2.7%) additional pregnancy but missed 5 (13.5%) pregnancies which subsequently developed preterm PE identified by the FMF triple test. Adding inhibin-A missed 4 (10.8%) pregnancies and did not identify any additional pregnancies with preterm PE.

CONCLUSION

Replacing PlGF by inhibin-A or adding inhibin-A as an additional biomarker in and to the FMF triple screening test for preterm PE does not improve screening performance and will fail to identify pregnancies that are currently identified by the FMF triple test.

Modified multiple marker aneuploidy screening as a primary screening test for preeclampsia

Background

Abnormal levels of maternal biochemical markers used in multiple marker aneuploidy screening have been associated with adverse pregnancy outcomes. This study aims to assess if a combination of maternal characteristics and biochemical markers in the first and second trimesters can be used to screen for preeclampsia (PE). The secondary aim was to assess this combination in identifying pregnancies at risk for gestational hypertension and preterm birth.

Methods

This case-control study used information on maternal characteristics and residual blood samples from pregnant women who have undergone multiple marker aneuploidy screening. The median multiple of the median (MoM) of first and second trimester biochemical markers in cases (women with PE, gestational hypertension and preterm birth) and controls were compared. Biochemical markers included pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PlGF), human chorionic gonadotropin (hCG), alpha feto-protein (AFP), unconjugated estriol (uE3) and Inhibin A. Logistic regression analysis was used to estimate screening performance using different marker combinations. Screening performance was defined as detection rate (DR) and false positive rate (FPR). Preterm and early-onset preeclampsia PE were defined as women with PE who delivered at < 37 and < 34 weeks of gestation, respectively.

Results

There were 147 pregnancies with PE (81 term, 49 preterm and 17 early-onset), 295 with gestational hypertension, and 166 preterm birth. Compared to controls, PE cases had significantly lower median MoM of PAPP-A (0.77 vs 1.10, p < 0.0001), PlGF (0.76 vs 1.01, p < 0.0001) and free-β hCG (0.81 vs. 0.98, p < 0.001) in the first trimester along with PAPP-A (0.82 vs 0.99, p < 0.01) and PlGF (0.75 vs 1.02, p < 0.0001) in the second trimester. The lowest first trimester PAPP-A, PlGF and free β-hCG were seen in those with preterm and early-onset PE. At a 20% FPR, 67% of preterm and 76% of early-onset PE cases can be predicted using a combination of maternal characteristics with PAPP-A and PlGF in the first trimester. The corresponding DR was 58% for gestational hypertension and 36% for preterm birth cases.

Conclusions

Maternal characteristics with first trimester PAPP-A and PlGF measured for aneuploidy screening provided reasonable accuracy in identifying women at risk of developing early onset PE, allowing triage of high-risk women for further investigation and risk-reducing therapy. This combination was less accurate in predicting women who have gestational hypertension or preterm birth.

Serum Inhibin-A and PAPP-A2 in the prediction of pre-eclampsia during the first and second trimesters in high-risk women

OBJECTIVES

Maternal serum inhibin-A, pregnancy associated plasma protein-A (PAPP-A) and PAPP-A2 together with placental growth factor (PlGF), maternal risk factors and uterine artery pulsatility index (UtA PI) were analysed to study their ability to predict pre-eclampsia (PE).

STUDY DESIGN

Serial serum samples for the nested case-control study were collected prospectively at 12-14, 18-20 and 26-28 weeks of gestation from 11 women who later developed early-onset PE (EO PE, diagnosis < 34 + 0 weeks of gestation), 34 women who developed late-onset PE (LO PE, diagnosis ≥ 34 + 0 weeks) and 89 controls.

MAIN OUTCOME MEASURES

Gestational age -adjusted multiples of the median (MoM) values were calculated for biomarker concentrations. Multivariate regression analyses were performed to combine first trimester biomarkers, previously reported results on PlGF, maternal risk factors and UtA PI. Area under curve (AUC) values and 95% confidence intervals (CIs) for the prediction of PE and its subtypes were calculated.

RESULTS

A high first trimester inhibin-A predicted PE (AUC 0.618, 95%CI, 0.513-0.724), whereas PAPP-A and PlGF predicted only EO PE (0.701, 0.562-0.840 and 0.798, 0.686-0.909, respectively). At 26-28 weeks PAPP-A2 and inhibin-A predicted all PE subtypes. In the multivariate setting inhibin-A combined with maternal pre-pregnancy body mass index, prior PE and mean UtA PI predicted PE (0.811,0.726-0.896) and LO PE (0.824, 0.733-0.914).

CONCLUSIONS

At first trimester inhibin-A show potential ability to predict not only EO PE but also LO PE whereas PlGF and PAPP-A predict only EO PE. At late second trimester inhibin-A and PAPP-A2 might be useful for short-term prediction of PE.

Cerebrospinal Fluid Protein Changes in Preeclampsia

The molecular mechanisms underlying seizure susceptibility in preeclampsia are unknown. We hypothesized that altered expression of distinct proteins in the cerebrospinal fluid (CSF) may reflect pathophysiological changes in the central nervous system that contribute to the neurological manifestations of severe preeclampsia. We obtained CSF samples from 13 patients with preeclampsia and 14 control patients during spinal anesthesia before delivery and analyzed them by SOMAscan, an aptamer-based proteomics platform for alterations in 1310 protein levels. Ingenuity Pathway Analysis was conducted to highlight relationships between preeclampsia-specific proteins found to be significantly altered. For 2 of the target proteins, we validated the difference in CSF concentrations by ELISA. SOMAscan revealed 82 proteins, whose expression levels were significantly different (P<0.05) in CSF from patients with preeclampsia versus controls. Principal component analysis achieved perfect separation of the preeclampsia and control groups in 2 dimensions. The differentially expressed proteins converge around 4 signaling molecules: TGF-β (transforming growth factor-β), VEGFA (vascular endothelial growth factor A), angiotensinogen, and IL-6 (interleukin-6). Within the TGF-β pathway, upregulation of activin A (301.6±47.4 versus 151.6±20.5 pg/mL; P=0.0074) and follistatin-related gene (5129±347 versus 3016±188 pg/mL; P<0.0001) in preeclampsia was confirmed by ELISA. In summary, signaling pathways important for vascular remodeling, inflammation, and neuronal growth, signaling, and electrophysiology were well represented among the proteins found to be altered in CSF in patients with preeclampsia.

Serum inhibin and leptin: Risk factors for pre-eclampsia?

BACKGROUND

Pre-eclampsia and eclampsia are parts of the broader spectrum of hypertensive disorders complicating pregnancy. This study aims to examine the association between serum inhibin and leptin levels and pre-eclampsia.

METHODS

This study included 98 consecutive cases of pregnant women with pre-eclampsia, together with their 98 pregnant controls, matched for age, gestational week and time period of delivery. Maternal venous blood samples were obtained within 24h before delivery. In addition to serum inhibin and leptin, birth order, multiple pregnancy, maternal age, maternal overweight/obesity, maternal education, maternal smoking and family history of diabetes/hypertension, were examined as risk factors. Multivariate logistic regression analysis was performed.

RESULTS

At the univariate analysis, serum inhibin and leptin levels were significantly higher in cases vs.

CONTROLS

Pre-eclampsia occurred more frequently in primiparous women, whereas overweight and obesity were also associated with pre-eclampsia. At the multivariate analysis, higher serum inhibin levels were associated with pre-eclampsia (multivariate OR=1.09, 95%CI: 1.03-1.17, p=0.004, increase per 0.1ng/mL). On the other hand, leptin was not independently associated with the occurrence of pre-eclampsia (multivariate OR=1.02, 95%CI: 0.95-1.09, p=0.631, increase per 10ng/mL).

CONCLUSIONS

Elevated serum inhibin levels seem to be associated with pre-eclampsia, reflecting placental dysfunction. Increased serum leptin levels may merely reflect an elevated maternal body mass index, which is a well-known risk factor for pre-eclampsia.

Circulating predictive biomarkers in preeclampsia

The aim of the paper was to review promising prediction biomarkers for preeclampsia. The methods included review of abstracts on PubMed, using "preeclampsia", "biomarker", "prediction" as key words, followed by review of primary papers investigating blood based biomarkers. Angiogenic factors, such as PlGf and sFlt1, and PP13 seem presently to have the best predictive test values for preeclampsia, but sensitivity and specificity is still too low to prove useful in a population screening setting. Biomarker testing should still be part of research protocols. Biomarkers could provide useful in selecting high-risk women for prophylactic trials as well as identifying pregnancies that could profit from closer follow-up.

Prediction of adverse pregnancy outcomes by combinations of first and second trimester biochemistry markers used in the routine prenatal screening of Down syndrome

OBJECTIVE

To investigate the associations between four defined adverse pregnancy outcomes and levels of first and second trimester maternal serum markers focusing in particular on how well combinations of markers predict these adverse outcomes.

METHODS

This was a retrospective review of associations between first and second trimester serum markers and adverse pregnancy outcomes among 141 698 women who underwent prenatal screening for Down syndrome in Ontario, Canada. Detection rates (DR), false positive rates (FPR), and odds ratios were estimated using both single and combinations of markers for the adverse outcomes defined.

RESULTS

Women with decreased second trimester unconjugated oestriol (uE3), deceased first trimester maternal serum pregnancy-associated plasma protein A (PAPP-A), increased second trimester serum alpha fetoprotein (AFP), or increased second trimester total human chorionic gonadotrophin (hCG) were at greater risk of developing adverse pregnancy outcomes. At a 5% FPR, combinations of these markers predicted at best 33.3% of fetal loss and 31.5% of preterm births (PTB) before 32 weeks of gestation.

CONCLUSION

There are significant associations between the levels of first and second trimester serum markers and adverse obstetric outcomes. However, even combinations of these markers can only predict adverse obstetric outcomes with modest accuracy.

The ability of the quadruple test to predict adverse perinatal outcomes in a high-risk obstetric population

OBJECTIVE

To determine the ability of the quadruple Down's syndrome screening test (quad screen) to predict other adverse perinatal outcomes (APO) in a high-risk obstetric population.

SETTING

A tertiary medical centre in West Virginia.

METHODS

We retrospectively reviewed 342 obstetric patients with quad screen data from a single clinic. The quad screen included maternal serum levels of alphafetoprotein (AFP), human chorionic gonadotrophin (hCG), uncongjugated oestriol (uE(3)), and inhibin A. The risk of APO was compared between patients with at least one abnormal marker versus no abnormal markers and >or=2 abnormal markers versus <2 abnormal markers. Abnormal markers were determined by cut-off values produced by Receiver Operator Characteristic (ROC) curves and the FASTER trial. Unadjusted and adjusted effects were estimated using logistic regression analysis.

RESULTS

The risk of having an APO increased significantly for patients with abnormal markers by about three-fold using ROC and two-fold using FASTER trial thresholds.

CONCLUSIONS

The quad screen shows value in predicting risk of APO in high-risk patients.

Markers for Presymptomatic Prediction of Preeclampsia and Intrauterine Growth Restriction

Preeclampsia and intrauterine growth restriction are both characterized by placental malfunction. The pathological processes of abnormal trophoblast invasion, partial absence of maternal spiral artery modification, increased apoptosis of trophoblast cells, and placental ischemia are all associated with the release of specific molecules. These proteins, as well as cell-free fetal DNA and RNA might be detected in the maternal peripheral circulation, quantified, and used for early identification and prediction of preeclampsia and intrauterine growth restriction, prior to the appearance of the clinical symptoms. As preeclampsia and intrauterine growth restriction are associated with increased maternal, perinatal, and neonatal morbidity and mortality, early identification of these pregnancy associated complications will permit the design of appropriate preventive measures. In this review a variety of factors reported to be useful as potential markers for early detection of pregnancies at increased risk will be discussed. Molecules associated with the establishment of the placenta and essential in fetal-maternal interactions, like interleukin 2-receptor, insulinlike growth factor-1, and insulinlike growth factor binding protein-1, placenta growth factor, hepatocyte growth factor, inhibin A, activin A, and human chorionic gonadotrophin seem to be the most likely candidates for presymptomatic markers for preeclampsia and/or intrauterine growth restriction. Detection and discrimination of these molecules through the placental RNA in maternal plasma based strategy has become a realistic option.

Down syndrome biochemical markers and screening for preeclampsia at first and second trimester: correlation with the week of onset and the severity

OBJECTIVES

To estimate the combined screening performance of first and early second trimester prenatal serum markers for Down syndrome, in screening for the development of preeclampsia, and analyze the correlation among marker levels, week of onset, and severity of the disease.

METHODS

A retrospective cohort study was carried out on 32 women with preeclampsia and 3044 controls. Serum samples from these pregnancies were assayed for pregnancy-associated plasma protein-A (PAPP-A), alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotrophin (hCG), and inhibin-A. A likelihood ratio and the odds of being affected given a positive result (OAPR) of various combinations of markers were calculated and receiver operating characteristic (ROC) curves analysis was performed.

RESULTS

In the pregnancies that subsequently developed preeclampsia, first trimester PAPP-A concentration was significantly lower and concentrations of early second trimester inhibin-A and hCG significantly elevated. Levels of early second trimester uE3 and AFP were not significantly altered. We also found that inhibin-A correlates with both onset of the disease and the severity.

CONCLUSION

Down syndrome biochemical markers levels are altered in those patients who subsequently developed preeclampsia and may be a useful screening test for preeclampsia. Inhibin-A is the most predictive marker and correlates with the severity of subsequent preeclampsia and inversely with the week of occurrence of preeclampsia.

Increased levels of pregnancy-associated plasma protein-A2 in the serum of pre-eclamptic patients

Pregnancy-associated plasma protein-A and -A2 (PAPP-A and -A2) are proteases that cleave insulin-like growth factor-binding proteins (IGFBPs), resulting in local activation of IGF signaling pathways. Here, we examined PAPP-A and -A2 mRNA and protein levels in placenta and maternal sera from women with pre-eclampsia and compared them with samples from uncomplicated pregnancy. PAPP-A2 but not PAPP-A mRNA and protein were elevated in pre-eclamptic placenta (P < 0.01). PAPP-A2 is normally produced in placental syncytiotrophoblast cells and maternal decidua. PAPP-A2 in syncytiotrophoblast cells was dramatically increased in pre-eclampsia. Maternal serum concentrations of PAPP-A2 but not PAPP-A were also significantly elevated in pre-eclampsia as compared with uncomplicated pregnancy. mRNA levels of IGFBP5, a specific substrate for PAPP-A2 protease activity, were also significantly increased, suggesting a potential role for IGFBP5 in fetal and placental growth suppression during pre-eclampsia. However, IGFBP5 protein levels were not increased in placenta from pre-eclampsia, possibly due to cleavage by up-regulated PAPP-A2. These data might imply that PAPP-A2 may be up-regulated in pre-eclamptic pregnancy to compensate for IGFBP5-mediated suppression of the IGF pathway, although final birthweights are still low in pre-eclamptic pregnancy.

First-trimester serum levels of soluble endoglin and soluble fms-like tyrosine kinase-1 as first-trimester markers for late-onset preeclampsia

OBJECTIVE

The aim of this investigation was to assess soluble endoglin (sEng) and soluble fms-like tyrosine kinase-1 (sFlt1) as first-trimester serum markers to predict preeclampsia.

STUDY DESIGN

First-trimester sera were obtained from 46 women with subsequent late-onset preeclampsia and from 92 controls. sEng and sFlt1 concentrations were determined immunoanalytically. Correlation analysis with inhibin A and placental growth factor levels was performed.

RESULTS

sEng and sFlt1 serum concentrations were higher in women with subsequent preeclampsia than in controls (mean +/- SD, sEng: 5.57 +/- 1.18 ng/mL vs 5.02 +/- 1.01 ng/mL, P = .009; sFlt1: 1764 +/- 757 pg/mL vs 1537 +/- 812 pg/mL, P = .036). Sensitivities and specificities for predicting preeclampsia were 63% and 57% for sEng and 64% and 56% for sFlt1, respectively. When sEng and inhibin A were combined, the sensitivity increased to 68%, whereas the specificity was 61%.

CONCLUSION

sEng and sFlt1 are increased in the first trimester in women with subsequent late-onset preeclampsia and might therefore prove useful to predict preeclampsia.

Inhibins as diagnostic markers in human reproduction

Over the past 75 years, many publications have focused on measurement of inhibin concentration and/or activity in biological samples in order to understand its role in physiology and disease. This chapter highlights the accomplishments within this area of research over the past decade including development of specific inhibin assays. Inhibin A is a marker of dominant follicle and corpus luteum activity and decreases in polycystic ovary syndrome (PCOS). Inhibin A increases in gestational diseases such as pre-eclampsia and fetal Down's syndrome, and this increase in inhibin A improves early diagnosis of both conditions. The measurement of inhibin A in women with threatened abortion provides useful information about the likelihood of pregnancy loss. Inhibin B increases markedly in women with granulosa cell tumor and appears closely related to gametogenesis in men, that is, reflecting Sertoli cell activity. On the contrary, Inhibin B decreases in women with declining ovarian function and correlates with female response to ovulation induction. This review evaluates the biochemical significance ofinhibins including their use in clinical practice.

Overproduction of the follistatin-related gene protein in the placenta and maternal serum of women with pre-eclampsia

OBJECTIVE

To characterise the follistatin-related gene (FLRG) in pre-eclampsia, one of the differentially expressed genes in pre-eclamptic placenta.

DESIGN AND METHODS

We examined and compared the messenger RNA (mRNA) and protein levels of FLRG in placentas and maternal sera from women with uncomplicated pregnancy, and those with pre-eclampsia using real-time reverse transcription polymerase chain reaction, Western blot, immunohistochemistry, and enzyme-linked immunosorbent assay.

SETTING

Antenatal clinics in a teaching hospital.

POPULATION

Women with uncomplicated pregnancy (n = 21) and those with pre-eclampsia (n = 21).

RESULTS

FLRG mRNA is overexpressed in pre-eclamptic placental tissues (P < 0.01). Upregulated FLRG protein consists of both an immature 28-kDa cellular product and a mature 33-kDa secretory form, which are differentially glycosylated. FLRG is normally produced at its highest levels in endothelial cells and at moderate amounts in syncytiotrophoblast cells, but in pre-eclampsia, the syncytiotrophoblast FLRG levels are dramatically increased. We also determined the maternal serum concentrations of FLRG in our uncomplicated pregnancy subjects and in our pre-eclamptic groups, and found that they are significantly elevated in pre-eclampsia in a similar manner to activin A and inhibin A. However, the increase in FLRG in these cases is independent of activin A or inhibin A, and is associated with low-birthweight outcomes.

CONCLUSION

Our current data show the placental and secretory changes of FLRG protein in pre-eclampsia, and also indicate the potential usefulness of FLRG as an additional diagnostic marker for pre-eclampsia.

Second-trimester uterine artery Doppler pulsatility index and maternal serum PP13 as markers of pre-eclampsia

OBJECTIVE

To evaluate whether measurement of maternal serum PP13 at 22 to 24 weeks of gestation, alone or in combination with second-trimester biochemical markers or uterine artery pulsatility measured by Doppler velocimetry, is useful in predicting those women at risk of developing pre-eclampsia.

STUDY DESIGN

A nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. PP13 was tested by an ELISA, with the samples blinded to pregnancy outcome. All patients also underwent uterine artery Doppler flow velocimetry at 22-24 weeks to measure the mean pulsatility index (PI). Results for Inhibin, Activin, PAPP-A and Free beta-hCG were available from previous studies.

RESULTS

There were 73 controls and five cases with early pre-eclampsia in which delivery was induced prior to 35 weeks. In addition, there were a further seven cases with pre-eclampsia in which delivery was not induced before term. Median PP13 levels for controls and all cases were 295.9 and 212.6 pg/ml, and 171.2 pg/ml amongst the early pre-eclampsia cases, with the MoMs 1.00, 0.94 and 0.63, respectively (p < 0.001). Receiver operator characteristic (ROC) curve analysis for either all cases or early cases versus controls yielded areas under the curve of 0.588 (95% CI: 0.42-0.76; p = 0.1526) and 0.693 (0.47-0.92; p = 0.0441) for PP13. At a specificity set to 0.80, the sensitivity for PP13 in the early cases was 0.40 and that in all cases was 0.25. Combining PP13 bivariately with any of the markers (PI, PAPP-A, Activin, Inhibin or Free beta-hCG) tested in the 22-24 week period did not improve the detection of early, late or all cases of pre-eclampsia compared with either marker alone.

CONCLUSION

Late second-trimester PP13 alone is unlikely to be useful in predicting pre-eclampsia and early pre-eclampsia, and its prediction does not increase when coupled with second-trimester Doppler PI or other potential biochemical markers. Measuring between-trimester temporal changes may be worthy of further investigation.

First-trimester maternal serum PP-13, PAPP-A and second-trimester uterine artery Doppler pulsatility index as markers of pre-eclampsia

OBJECTIVE

To evaluate whether measurement of maternal serum placental protein-13 (PP-13) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks of gestation alone or in combination with second-trimester uterine artery pulsitility measured by Doppler velocimetry is useful in predicting those women who will develop pre-eclampsia

METHODS

This was a nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. Samples were collected as part of a first-trimester prenatal chromosomal anomaly screening program and were routinely tested for PAPP-A. PP-13 was tested using an enzyme linked immunosorbent assay (ELISA) by an examiner who was blinded to pregnancy outcome. All patients also underwent uterine artery Doppler flow velocimetry to measure the mean pulsatility index (PI) at 22-24 weeks' gestation.

RESULTS

There were 446 controls and 44 cases with early pre-eclampsia where delivery was induced prior to 35 weeks. In addition there were a further 44 cases with pre-eclampsia in which delivery was not induced before term. Median PP-13 levels for controls, all cases and early pre-eclampsia cases were 176.9, 121.9 and 111.7 pg/mL, with multiples of the median (MoMs) of 1.00, 0.69 and 0.63, respectively (P < 0.001). PAPP-A MoMs were 1.00, 0.89 (P = 0.076) and 0.89 (P = 0.042) and mean PIs were 1.0, 1.6 (P < 0.001) and 1.7 (P < 0.001) for controls, all cases and early cases, respectively. Receiver-operating characteristics (ROC) curve analysis for either all cases or early cases vs. controls yielded areas under the curve for PP-13, PAPP-A and PI respectively of 0.68 (95% CI, 0.61-0.74; P < 0.001), 0.56 (95% CI, 0.49-0.63; P = 0.076) and 0.79 (95% CI, 0.72-0.87; P < 0.001) for all cases and 0.71 (95% CI, 0.63-0.79; P < 0.001), 0.59 (95% CI, 0.51-0.68; P = 0.076) and 0.86 (95% CI, 0.77-0.94; P < 0.001) for early cases. At a specificity set to 0.80 the sensitivities were 0.50, 0.23 and 0.76 for PP-13, PAPP-A and PI in the early cases and 0.44, 0.24 and 0.73 in all cases. Combining PP-13 and PI using logistic regression analysis yielded an area under the curve of 0.84 (95% CI, 0.78-0.90; P < 0.001) and a sensitivity of 0.74 in all cases, and 0.90 (95% CI, 0.84-0.96; P < 0.001) and a sensitivity of 0.79 for early cases. PAPP-A with PI gave an area under the curve of 0.82 (95% CI, 0.76-0.90; P < 0.001) and a sensitivity of 0.76 in all cases. Combining PAPP-A with PP-13 and PI did not add significantly to the sensitivity.

CONCLUSION

First-trimester PP-13 levels may be useful in predicting pre-eclampsia and early pre-eclampsia, and the accuracy of the method increases when coupled with second-trimester Doppler PI measurement. First-trimester PAPP-A provides some prediction for pre-eclamspia when combined with PI but does not add to the prediction of early pre-eclampsia when PP-13 and PI are used together. Further studies are required to establish the real value of PP-13 in first-trimester screening for pre-eclampsia.

Serum and urine inhibin A but not free activin A are endocrine biomarkers of severe pre-eclampsia

OBJECTIVE

Elevation of total serum inhibin A and activin A has been interpreted as evidence of placental dysfunction in women who develop pre-eclampsia. We sought to evaluate serum and urine levels of inhibin A and free activin A in normal and hypertensive pregnancies.

STUDY DESIGN

Inhibin A and free activin A were measured by immunoassay in simultaneously collected serum and urine samples from 75 women: (1) severe pre-eclampsia (n = 30); (2) mild pre-eclampsia (n = 11); (3) chronic hypertension (n = 9); (4) pregnant control women (n = 16); and (5) nonpregnant control women (n = 9). Urine levels were normalized to milligrams urine creatinine, and fractional excretions were calculated.

RESULTS

Serum and urine inhibin A were increased and fractional excretion was decreased in pregnancy. Serum, urine, and fractional excretion of inhibin A were increased in severe pre-eclampsia, compared with other gravidas. The only difference observed in free activin A was a decrease in serum free activin A in chronic hypertension, compared with severe pre-eclampsia and pregnant control women. Urine inhibin A showed the greatest discrimination between severe pre-eclampsia and pregnant control women: a cut-off of 45 pg/mg urine creatinine had 96.8% sensitivity, 87.5% specificity, and 93.6% accuracy. Women with urine inhibin A greater than 90 pg/mg urine creatinine had a 17-fold relative risk (95% confidence interval 9.7-459.5) of a clinically indicated delivery due to pre-eclampsia.

CONCLUSION

Serum and urine levels of inhibin A are altered in severe pre-eclampsia. Urine inhibin A may have application in the diagnosis and management of pre-eclampsia. Those with chronic hypertension have lower serum but not urine free activin A levels, compared with severe pre-eclampsia and mild pre-eclampsia.

First Trimester Markers for Pre-Eclampsia: Placental vs. Non-Placental Protein Serum Levels

BACKGROUND/AIM

Parallel investigation, in a matched case-control study, of the association of different first-trimester markers with the risk of subsequent pre-eclampsia (PE).

METHOD

The levels of different first trimester serum markers and fetal nuchal translucency thickness were compared between 52 cases of PE and 104 control women by non-parametric two-group comparisons and by calculating matched odds ratios.

RESULTS

In univariable analysis increased concentrations of inhibin A and activin A were associated with subsequent PE (p < 0.02). Multivariable conditional logistic regression models revealed an association between increased risk of PE and increased inhibin A and translucency thickness and respectively reduced pregnancy-associated plasma protein A (PAPP-A) and placental lactogen . However, these associations varied with the gestational age at sample collection. For blood samples taken in pregnancy weeks 12 and 13 only, increased levels of activin A, inhibin A and nuchal translucency thickness, and lower levels of placenta growth factor and PAPP-A were associated with an increased risk of PE.

CONCLUSIONS

Members of the inhibin family and to some extent PAPP-A and placental growth factor are superior to other serum markers, and the predictive value of these depends on the gestational age at blood sampling. The availability of a single, early pregnancy 'miracle' serum marker for PE risk assessment seems unlikely in the near future.

Prediction of pre-eclampsia by uterine artery Doppler ultrasonography and maternal serum pregnancy-associated plasma protein-A, free beta-human chorionic gonadotropin, activin A and inhibin A at 22 + 0 to 24 + 6 weeks' gestation

OBJECTIVE

To investigate the potential value of combining uterine artery Doppler ultrasonography with the measurement of maternal serum pregnancy-associated plasma protein-A (PAPP-A), free beta-human chorionic gonadotropin (beta-hCG), activin A and inhibin A at 22 + 0 to 24 + 6 weeks' gestation, in the prediction of pregnancies that subsequently develop pre-eclampsia.

METHODS

The maternal serum PAPP-A, free beta-hCG, activin A and inhibin A concentrations at 22 + 0 to 24 + 6 weeks' gestation were measured in samples obtained from women with singleton pregnancies who participated in a screening study for pre-eclampsia by transvaginal color flow Doppler measurement of the uterine artery pulsatility index (PI). A search was made of the database to identify those who subsequently developed pre-eclampsia (n = 24) and a group of controls with normal outcome (n = 144). Regression analysis was performed to establish any relationship between the biochemical markers themselves and between the biochemical markers and uterine artery mean PI. A multivariate Gaussian model combining various biochemical markers with uterine artery mean PI was developed using standard statistical modeling techniques and the performance of such models in discriminating cases with pre-eclampsia was evaluated by receiver-operating characteristics curve (ROC) analysis.

RESULTS

In the pre-eclampsia group, compared to the controls, the uterine artery mean PI and the maternal serum levels of PAPP-A, free beta-hCG, activin A and inhibin A were significantly increased. The predicted detection rates of pre-eclampsia, for a false positive rate of 5%, was 50% by uterine artery mean PI, 5% by PAPP-A, 10% by free beta-hCG, 35% by inhibin A and 44% by activin A. Screening by a combination of uterine artery mean PI and maternal serum activin A and inhibin A could detect 75% and 92% of patients who subsequently developed pre-eclampsia, for false positive rates of 5% and 10%, respectively.

CONCLUSION

Screening for pre-eclampsia by uterine artery PI at 22 + 0 to 24 + 6 weeks' gestation can be improved by measurement of activin A and inhibin A levels.

Maternal serum and amniotic fluid inhibin A levels in women who subsequently develop severe preeclampsia

The purpose of this study was to evaluate whether maternal serum (MS) and amniotic fluid (AF) inhibin A levels are elevated in patients who subsequently develop severe preecalmpsia, and to investigate the correlation between MS and AF inhibin A levels in the second trimester. The study included 40 patients who subsequently developed severe preecalmpsia and 80 normal pregnant women. Inhibin A levels in MS and AF were measured with enzyme-linked immunosorbent assay (ELISA). The MS and AF inhibin A levels in patients who developed severe preeclampsia were significantly higher than those in the control group (both for p<0.001). There was a positive correlation between MS and AF inhibin A levels in patients who developed severe preeclampsia (r=0.397, p=0.011), but not in the control group (r=0.185, p=0.126). The best cutoff values of MS and AF inhibin A levels for the prediction of severe preeclampsia were 427 pg/mL and 599 pg/mL, respectively; the estimated ORs that were associated with these cut-off values were 9.95 (95% CI 3.8-25.9, p<0.001) and 6.0 (95% CI 2.3-15.8, p<0.001). An elevated level of inhibin A in MS and AF at the time of second trimester amniocentesis may be a risk factor for the subsequent development of severe preeclampsia.

Uterine vein and maternal urinary levels of activin A and inhibin A in pre-eclampsia patients

OBJECTIVES

The aims of this study were to investigate if (i) urinary concentrations of activin A and inhibin A are altered in pre-eclampsia (PE) and (ii) to study the relationship between uterine vein and peripheral vein concentrations of these hormones in PE patients.

DESIGN AND METHOD

In a retrospective study, maternal peripheral vein and uterine vein serum and maternal urine samples collected at the time of delivery were analysed. There were three groups of patients; (i) group 1: term normal pregnancies (n = 19) (ii) group 2: patients who developed PE < or = 37 weeks (n = 17) and (iii) group 3: patients who developed PE 37-40 weeks (n = 8). Serum and urinary activin A, follistatin, inhibin A and pro alpha C and urinary creatinine levels were measured using enzyme immunoassays in the laboratory.

RESULTS

Normal pregnant urine samples had very low levels of activin A and inhibin A. Both groups 2 and 3 PE patients had significantly higher levels of inhibin A (P < 0.001) and activin A (P < 0.001) compared to the controls. Pro-alpha C was not altered and follistatin was below the detection limit of the assay in the urine. Maternal peripheral serum activin A and inhibin A were significantly higher in groups 2 (P < 0.001) and 3 (P < 0.05) patients compared to the controls. Pro-alpha C-containing inhibins were higher in group 2 patients (P < 0.05) compared to the controls in the peripheral circulation. Uterine vein serum activin A and inhibin A levels were also significantly higher in groups 2 (P < 0.001) and 3 (P < 0.05) patients compared to the controls. There was a highly significant positive correlation between peripheral and uterine vein serum concentrations of activin A, follistatin, inhibin A and pro alpha C, suggesting the same source for these proteins in PE.

CONCLUSION

Urinary activin A and inhibin A are raised in groups 2 and 3 PE patients. The magnitude of rise (> 25-fold) suggests these proteins may rise in patients before the onset of the clinical symptoms of PE. Uterine vein levels of these proteins are also raised in PE.

Screening for pre-eclampsia by using maternal serum inhibin A, activin A, human chorionic gonadotropin, unconjugated estriol, and alpha-fetoprotein levels and uterine artery Doppler in the second trimester of pregnancy

AIMS

To analyse the predictive power of maternal serum inhibin A, activin A, human chorionic gonadotropin (hCG), unconjugated estriol (uE(3)), alpha-fetoprotein (AFP) levels and uterine artery Doppler in the second trimester of pregnancy in screening for pre-eclampsia.

METHODS

Maternal serum inhibin A, activin A, hCG, uE(3), and AFP levels and uterine artery Doppler were determined in 178 healthy, pregnant women in the second trimester of pregnancy. Serum samples were collected between the 16th and 18th weeks of gestation, and Doppler investigation was performed between the 24th and 26th weeks of gestation. Receiver operating characteristic curves were created to analyse the predictive powers of the above parameters in screening for pre-eclampsia. Different combinations also were analysed.

RESULTS

The rate of pre-eclampsia was 7.9% (14/178). Maternal serum inhibin A, activin A, hCG, AFP levels, the rate of presence of the prediastolic notch and uterine artery resistance index (RI) values in pre-eclamptic pregnancies were significantly higher than those in healthy pregnancies. Presence of the prediastolic notch, uterine artery RI, maternal serum activin A and inhibin A levels had high predictive efficacy, and each had a sensitivity between 70 and 93% and a specificity between 87% and 98%. The addition of inhibin A or activin A measurement to the Doppler velocimetry improved the specificity to 99-100%.

CONCLUSIONS

Maternal serum inhibin A and activin A levels and uterine artery Doppler appear to be useful screening tests during the second trimester for pre-eclampsia. However, addition of these hormonal markers to Doppler velocimetry only slightly improves the predictive efficacy, which appears clinically insignificant.

Activin and follistatin in female reproduction

Activin and follistatin were initially identified in the follicular fluid based on their effects on pituitary FSH secretion in the mid-1980s. It is now evident that activin, follistatin and activin receptors are widely expressed in many tissues where they function as autocrine/paracrine regulators of a variety of physiological processes including reproduction. The major function of follistatin is to bind to activin with high affinity and block activin binding to its receptors. Total activin A and follistatin are also found in the maternal circulation throughout pregnancy. Activin A levels are increased in abnormal pregnancies such as pre-eclampsia, fetal growth restriction and gestational hypertension. The placenta, vascular endothelial cells and activated peripheral mononuclear cells (PBMC) may all contribute to the raised levels of activin A in pre-eclampsia with unaltered follistatin in pre-eclamptic placenta, PBMCs or vascular endothelial cells suggesting the availability of 'free' activin A that could be biologically active in these cells.

Prediction of preeclampsia: can it be achieved?

In this review, the various biochemical tests that have been proposed for the prediction of preeclampsia are described and evaluated. Placenta hormone markers do not predict future disease. They denounce the early placental changes that are part of the evolving disease and only predict the imminent of preeclamptic syndrome. This explains why tests are better predictors when preeclampsia supervenes shortly, and why screening in the first trimester is unlikely to work as well as in the second trimester. The use of multiple markers in the screening should reflect different aspects of the disease process and could increase the specificity and sensitivity of the screening and work on different etiologic factors. The possible use of second-trimester biochemical screening to predict the risk of preeclampsia remains to be investigated in the high-risk population.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to list the various theories on the etiology of preeclampsia, to relate the various risk factors for the development of preeclampsia, and to describe the various screening tests for preeclampsia.

Severe preeclampsia is associated with high inhibin A levels and normal leptin levels at 7 to 13 weeks into pregnancy

OBJECTIVE

The purpose of this study was to determine whether maternal serum inhibin A and leptin concentrations changed in the first trimester of pregnancy in patients in whom severe preeclampsia subsequently developed.

STUDY DESIGN

Blood samples were collected prospectively from patients during the first trimester of prenatal care. Patients in whom severe preeclampsia with no evidence of glucose intolerance or gestational diabetes mellitus subsequently developed were identified (study group, 30 patients) and matched with control subjects in a 1:2 ratio (control group, 60 patients). Inhibin A and leptin concentrations were determined in these first-trimester serum samples for both the study and control groups.

RESULTS

Leptin levels were correlated highly with body mass index in both groups but were not correlated with the subsequent onset of preeclampsia. Serum inhibin A concentrations were significantly higher in women in whom preeclampsia subsequently developed than in women in whom it did not. With a specific cutoff value, the estimated odds for severe preeclampsia were almost five times higher in women with high inhibin A concentrations than in women with normal levels (odds ratio, 4.93; 95% CI, 1.83, 13.28).

CONCLUSION

High serum inhibin A levels in the first trimester of pregnancy could be used as an early risk marker for preeclampsia.

Prenatal screening, epidemiology, diagnosis, and management of preeclampsia

The cause of preeclampsia remains unknown. The disease manifests itself across a broad clinical spectrum from mild to severe, conferring vastly different morbidities and suggesting possibly different disease processes. Oxidative stress, endothelial dysfunction, maternal-fetal immune incompatibility, and abnormal placental implantation are among the suggested causes. The need for a marker or set of markers that allow for definitive diagnosis and assessment of future risk of preeclampsia is tremendous. Ultrasound techniques and several markers have been identified that are increased among patients with preeclampsia, but no test is highly sensitive. In the future, a combination of markers likely will be used to assess risk and, establish the diagnosis, and test treatment strategies. Such an approach would allow for more refined treatment studies of patients who are at highest risk for preeclampsia.

Women with preeclampsia have increased serum levels of pregnancy-associated plasma protein A (PAPP-A), inhibin A, activin A and soluble E-selectin

OBJECTIVE

Poor placentation in early pregnancy is thought to lead to an excessive maternal systemic inflammatory response, which causes the maternal syndrome of preeclampsia. The aims of this retrospective study were to confirm old reports of increased blood levels of pregnancy-associated plasma protein A (PAPP-A) in preeclampsia and how its levels correlate with the levels of other placental and endothelial proteins that are reported to be elevated in preeclampsia.

METHODS

Nineteen women with preeclampsia symptoms were matched with 19 normal pregnant controls for gestational age, maternal age, and parity. PAPP-A, placental pregnancy-specific beta1-glycoprotein (SP1), inhibin A, activin A, and sE-selectin were measured in serum using specific ELISAs.

RESULTS

Maternal serum levels of PAPP-A, inhibin A, activin A and sE-selectin were increased in women with preeclampsia (mean 157.7 vs. 76.85 mIU/mL, p=0.005; 3.08 vs. 1.51 ng/mL, p=0.002, 32.36 vs. 3.77 ng/mL, p<0.001 and 62.15 vs. 46.37 ng/mL, p=0.02 respectively), compared to controls. Serum levels of SP1 were not altered in preeclampsia. PAPP-A (r=0.636, p<0.01) had a positive correlation with sE-selectin in patients with preeclampsia. Serum inhibin A and activin A had a significant positive correlation with each other in preeclampsia.

CONCLUSIONS

Raised levels of PAPP-A in preeclampsia confirm earlier reports. Activin A showed the highest increase over the controls and is thus likely to be a better serum marker for this pathology than the other markers that were tested.

The role of hyperglycosylated hCG in trophoblast invasion and the prediction of subsequent pre-eclampsia

OBJECTIVE

Hyperglycosylated hCG (HhCG) is the predominant form of chorionic gonadotrophin in states characterized by aggressive trophoblast invasion such as early pregnancy or choriocarcinoma. Pre-eclampsia may be the result of failed or inadequate trophoblast invasion. We investigated whether low levels of maternal urine HhCG levels would predict subsequent pre-eclampsia.

STUDY DESIGN

Mid-trimester urine (14-21 weeks) was collected and frozen from non-hypertensive women undergoing genetic amniocentesis. Inclusion criteria were: normal singleton pregnancies without a prior history of pre-eclampsia, hypertension, diabetes or other vascular disorders. The specimens were subsequently thawed, and HhCG levels standardized to urine creatinine were measured. Maternal charts were reviewed after delivery to determine the development of pre-eclampsia. There were a total of 568 study subjects.

RESULTS

Pre-eclampsia developed in 26 (4.6%) women. There was a significant correlation between low urine HhCG and subsequent pre-eclampsia (Mantel-Haenszel test of linear association: Chi-square 10.52, p=0.001). The mean HhCG level (ng/mg creatinine) was significantly greater in normals than in those destined to develop pre-eclampsia: 42.7 versus 20.3, p=0.002 (Mann-Whitney U-test). There was a progressive increase in the risk of subsequent pre-eclampsia as HhCG levels fell: HhCG < or =0.9 MoM RR (95% CI)=1.51 (1.15-1.98) compared with < or =0.1 MoM 10.42 (2.0-54.3).

CONCLUSION

Low maternal mid-trimester urine HhCG predicted subsequent pre-eclampsia. This appears to support the view that pre-eclampsia results at least in part from poor trophoblast invasion. Thus, HhCG may play a role in trophoblast invasion and measurement of this in urine identifies women at high risk for developing pre-eclampsia.

Is mid-trimester maternal serum inhibin-A a marker of preeclampsia or intrauterine growth restriction?

BACKGROUND

To evaluate maternal serum Multiple of Median inhibin-A in mid-trimester blood samples of women who subsequently developed preeclampsia, gestational hypertension and intrauterine growth restriction and controls. Also, to verify whether this marker is related to these pathological conditions.

METHODS

Retrospective analysis of serum samples from a bank of stored serum, originally taken for Down's syndrome screening over 15-18 weeks, was performed. The sample consisted of 20 patients with gestational hypertension, 20 patients with preeclampsia, 10 patients with intrauterine growth restriction and 40 controls.

RESULTS

No statistically significant difference of inhibin-A Multiple of Median values between the control group and the preeclamptic or gestational hypertension groups was found. There was a statistically significant elevation in the intrauterine growth restriction group in comparison with the control group, and the same was true for each subgroup of gestational hypertension and preeclampsia complicated by intrauterine growth restriction.

CONCLUSION

Elevated maternal inhibin-A concentrations in the second trimester are strongly associated with intrauterine growth restriction and not with preeclampsia, as previously stated.

Predictive value of hormone measurements in maternal and fetal complications of pregnancy

Intrauterine tissues (placenta, amnion, chorion, decidua) express hormones and cytokines that play a decisive role in maternal-fetal physiological interactions. The excessive or deficient release of some placental hormones in association with gestational diseases may reflect an abnormal differentiation of the placenta, an impaired fetal metabolism, or an adaptive response of the feto-placental unit to adverse conditions. This review is focused on the applicability of hormone measurements in the risk assessment, early diagnosis, and management of pregnancies complicated by Down's syndrome, fetal growth restriction, preeclampsia, preterm delivery, and diabetes mellitus. Combined hormonal tests or the combination of hormones and ultrasound may achieve reasonable sensitivity, but research continues to simplify the screening programs without sacrificing their accuracy. Only in a few instances is there sufficient evidence to firmly recommend the routine use of hormone tests to predict maternal and fetal complications, but the judicious use of selected tests may enhance the sensitivity of the risk assessment based solely on clinical and ultrasound examination.

Changes in inhibins and activin secretion in healthy and pathological pregnancies

Inhibin-related proteins are involved in the control of the feto-maternal communication required to maintain pregnancy. Human placenta, decidua, and fetal membranes are the major sites of production and secretion of activin A, inhibin A and inhibin B in maternal serum, amniotic fluid, and cord blood. The availability of suitable assays developed in the last years has enabled the measurement of inhibins and activin A in their dimeric forms, in order to investigate their role in physiological conditions of pregnancy. The studies conducted on inhibin-related proteins and human pregnancy suggested the possibility of an involvement of inhibin A and activin A in the pathogenesis of gestational diseases. In fact, several lines of evidence underline the potential role and the clinical usefulness of inhibin-related proteins measurement in the diagnosis, prevention, prognosis and follow-up of different gestational pathologies such as early pregnancy viability, Down's syndrome, fetal demise, pre-eclampsia, pregnancy-induced hypertension, preterm delivery and intrauterine growth restriction. The measurement of inhibin A and activin A into the biological fluids of pregnancy will offer in the future, further possibilities in the early diagnosis, prediction, and monitoring diseases of pregnancy.

Measurement of inhibin A and activin A in pregnancy--possible diagnostic applications

Knowledge of the roles of inhibins and activins has progressed rapidly since the development of a specific and sensitive assay that can be used for measurements on human serum and amniotic fluid samples. There is a sound theoretical basis for the role of transforming growth factor-beta family members in inflammatory processes, many of which are analogous to implantation, parturition and a variety of pathological conditions in pregnancy. This review explores the potential use of assays for inhibins and activins in clinical practice and suggests further areas for research.